latency

## What I do - Measure and analyze network latency - Identify latency sources in systems - Design low-latency architectures - Optimize data transfer protocols - Implement caching strategies - Reduce round-trip times - Profile application performance ## When to use me Use me when: - Diagnosing slow network performance - Building real-time applications - Designing distributed systems - Optimizing user experience - Understanding network bottlenecks - Planning capacity and scaling ## Key Concepts ### Latency vs Bandwidth - **Latency**: Time for single packet (ms) - **Bandwidth**: Data per second (Mbps) - They affect performance differently: - Latency critical for interactive apps - Bandwidth critical for bulk transfers ### Speed of Light Limits - Fiber: ~200,000 km/s (2/3 c) - Theoretical minimum latency = distance / speed - Example: NYC to London ~70ms minimum ### Latency Components ``` Total Latency = ┌─────────────────┐ │ Processing │ (routers, switches) │ + Serialization │ (bits on wire) │ + Propagation │ (distance/speed of light) │ + Transmission │ (bandwidth limits) │ + Queuing │ (congestion) └─────────────────┘ ``` ### Measurement Tools - **ping**: RTT to host - **traceroute**: Path and per-hop latency - **WebPageTest**: Full page load analysis - **Chrome DevTools**: Network timing - **APM tools**: Application latency tracking ### Common Latency Targets | Application | Target Latency | |-------------|----------------| | Web (initial) | < 2 seconds | | API calls | < 200ms | | Real-time (gaming) | < 50ms | | Financial trading | < 1ms | | VoIP | < 150ms |